X-Series Dual Oscillator



The Macbeth x-series dual oscillator has been designed to facilitate the demands of the discerning user who seeks a high-end analogue oscillator combo for music synthesis. The unit is housed in a 42hp, 3u, eurorack module. this unit has been designed to address the need for larger controls, ergonomics and panel space associated with a larger format but now within the 3u format.

The primary advantage of using two oscillators over one (no matter how complex- some oscillators use sub-octaves, pwm, sawtooth animation etc ) is the ability to produce a rich and thick sound! two oscillators in near perfect unison sound wonderful- but fifths apart- or even ninths is fantastic. try dropping a third an octave below!

Features
Two temperature stabilized oscillators conforming to the standard 1v/octave logarithmic law used for scaling by most analogue synthesizers.

Each oscillator is equipped with a 10 turn frequency potentiometer- this allows for drastic tuning actions- as well as subtle tuning of thirds, fifths, ninths etc. the 10 turn frequency control replaces the more common 'course' and 'fine' tuning frequency controls normally found on analogue oscillators. Each oscillator is provided with a convenient 5 octave switch control making transposition easy.

Each oscillator features 6 waveforms, all individually accesable. the wave forms are: sawtooth, ramp, fixed square, variable rectangle, triangular and sine. There is a nominal pulse width control to manually control the duty cycle of the rectangular waveform. there is also an external pulse width modulation (pwm) input so that external control voltage can sweep the duty cycle of the wave form.

Both oscillators provide a range from around 1hz low frequency to beyond 25khz. Status led indicators give some indication of the oscillator 'state.' Each oscillator is provided with 1 attenuated 1v/octave log input, 1 1v/octave log input (fixed) and 1 linear cv input.

Included in the design are two further functions

The x-series dual oscillator features a genuine 'balanced modulator' wired up as a ring modulator. common practice amongst contemporary manufacturers is to use the ad633. that device is an analogue multiplier. it is inexpensive and easy to use. it comes close to providing ring modulation and requires few external parts. the dual oscillator features the mc1496 balanced modulator ic that was used commonly in the older synthesizers of the 1970s. this ic wired up as ring modulator offers considerably more ring mod character than the ad633 type.

The sine waveforms are 'normalised' into the ring modulator- but other waveforms can be patched in at will.

The x-series dual oscillator also features a variable white/pink noise generator. this circuit provides a pure and clean white noise output as well as lower frequency pink noise output. this again is another classic circuit built around an all transistor design.

The x-series modules are designed and built around the philosophy that 'old is best' - all the parts are chosen for their 'vintage character'. where possible- transistors only are used over the more common transistor-opamp designs. the resistors in these designs are ½ watt types- the are larger than the average through hole resistors.

The x-series steers well away from any surface mount technology!